Pneumatic tire

Abstract

An object of the present invention is to provide a pneumatic tire capable of facilitating heat dissipation of a tread portion thereof to lower temperature at the tread portion. Specifically, the present invention provides a pneumatic tire having in a tread surface at least one circumferential groove extending in the tire circumferential direction and plural lateral grooves, the lateral grooves each opening to the circumferential groove, having a wider groove width than the circumferential groove and extending to be inclined with respect to the tire circumferential direction, comprising: a recessed portion formed in a groove wall, facing the corresponding lateral groove, of the circumferential groove; and at least one projecting portion formed at a groove bottom of the circumferential groove between the recessed portions adjacent to each other in the tire circumferential direction.

What is claimed is: 
     
       1. A pneumatic tire having in a tread surface at least one circumferential groove extending in the tire circumferential direction and plural lateral grooves, the lateral grooves each opening to the corresponding circumferential groove and having a narrower groove width than the circumferential groove in a portion opening to the circumferential groove and a wider groove width than the circumferential groove in the remaining portion thereof, comprising:
 a plurality of recessed portions formed in a groove wall of each circumferential groove, each of the recessed portions facing the corresponding lateral groove; and 
 at least one projecting portion formed at a groove bottom of each circumferential groove between the recessed portions adjacent to each other in the tire circumferential direction, 
 wherein, provided that angle θ 1  and angle θ 2  are formed by one groove wall face ( 61 ) and another groove wall face ( 62 ) constituting a recessed portion ( 6 ) of the plurality of recessed portions, respectively, with respect to an imaginary extension of a groove wall ( 21 ) extending in the tire circumferential direction, of each circumferential groove ( 2 ), in a plan view of the tread, 
 0°<θ1<θ2≤90° and the recessed portion has an unsymmetrical configuration in the plan view, 
 provided that each recessed portion ( 6 ) is connected with the corresponding circumferential groove ( 2 ) at one connection point ( 6   a ) and the other connection point ( 6   b ) and that “point A” and “point B” represent intersections of imaginary extension lines of respective groove walls of each lateral groove ( 3 ) corresponding to the recessed portion, with the groove wall ( 21 )/the imaginary extension of the groove wall ( 21 ) of the circumferential groove ( 2 ), respectively, at least one of the one connection point ( 6   a ) and the other connection point ( 6   b ) is formed beyond the point A/the point B and a region between the point A and the point B, 
 wherein: 
 the at least one projecting portion is inclined with respect to the direction orthogonal to the corresponding circumferential groove in the plan view of the tread, 
 the groove wall face, forming the angle θ 2 , of each recessed portion is inclined in the same direction with respect to the corresponding circumferential groove as the at least one projecting portion corresponding to the circumferential groove is inclined with respect to the circumferential groove, 
 each circumferential groove extends straight in the tire circumferential direction, and 
 the pneumatic tire has in the tread surface at least two circumferential grooves each extending in the tire circumferential direction and plural lateral grooves each opening to the corresponding circumferential groove, and in an unworn state of the tire, each recessed portion of one circumferential groove has no groove connecting said recessed portion with the recessed portion of another adjacent circumferential groove, 
 at least one of the imaginary extension lines of respective groove walls of each lateral groove ( 3 ) intersects the another groove wall face ( 62 ) of the corresponding recessed portion ( 6 ), and 
 each of the at least one projecting portion is formed only at a position in the corresponding circumferential groove ( 2 ) between the groove wall face ( 62 ) forming the angle θ 2  of one of the recessed portions adjacent to each other in the tire circumferential direction and a halfway position between the other connection point ( 6   b ) of the one of the recessed portions adjacent to each other in the tire circumferential direction and the other connection point ( 6   b ) of the other of the recessed portions adjacent to each other in the tire circumferential direction.